An automatic shift apparatus disclosed in JP2012-225436A, hereinafter referred to as Reference 1, for example, includes a first clutch ring, a second clutch ring, a sleeve arranged between the first clutch ring and the second clutch ring to be movable in an axial direction, a shaft moving apparatus for moving the sleeve in the axial direction, and a control unit driving the shaft moving apparatus. The first clutch ring and the second clutch ring are fixed gears. The sleeve is a movable gear. The control unit controls the sleeve, which is in an engaged state with the first clutch ring by a dog clutch portion of the sleeve and a dog clutch portion of the first clutch ring being engaged, to move toward a neutral position defined at a position between the first clutch ring and the second clutch ring. More specifically, the sleeve is made to stop at the neutral position by exerting a force in the opposite direction relative to a direction of movement of the sleeve after the dog clutch portions of the sleeve and the first clutch ring are disengaged.
In recent years, automatic shift apparatuses with a separation distance reduced between the first clutch ring and the second clutch ring are developed. In the automatic shift apparatus disclosed in Reference 1, in a state where a mechanism includes looseness, the sleeve may contact the second clutch ring by swinging movement in the axial direction at a time at which movement of the sleeve is made to stop at the neutral position. In a state where rotational speed of the second clutch ring is high, a shift shock and a contact noise are generated as a result of the sleeve making contact with the second clutch ring, which are considered as disadvantages. The sleeve making contact with the second clutch ring may be avoided by moving the sleeve in a low speed, however, a shift time becomes longer, which is considered as a disadvantage.
A need thus exists for an automatic shift apparatus, which is not susceptible to the drawbacks mentioned above.